Cement sole attaching machine using high-frequency



Dec. 2, 1952 G. T. HART 2,619,651

CEMENT SOLE ATTACHING MACHINE USING HIGH-FREQUENCY Filed Jan. 19, 1950 9 Sheets-Sheet l George 7." H07"? Inventor.

G. T. HART Dec. 2, 1952 CEMENT SOLE ATTACHING MACHINE USING HIGH-FREQUENCY 9 Sheets-Sheet 2 Filed Jan. 19, 1950 George T Har'f Inventor G. T. HART Dec. 2, 1952 CEMENT SOLE ATTACHING MACHINE USING HIGH-FREQUENCY Filed Jan. 19, 1950 9 Sheets-Sheet 5 Inventor George 7. Her/"7" Dec. 2, 1952 r G. r. HART CEMENT SOLE ATTACHING MACHINE USING HIGH-FREQUENCY Filed Jan. 19, 1950 9 Sheetg-Sheet 4 Inventor George 77 Ham .5

Dec; 2, 1952 G. 1'. HART 2,619,661

CEMENT SOLE ATTACHING MACHINE USING HIGH-FREQUENCY Filed Jan. 19, 1950 9 Sheets-Sheet 5 Inventor George THarf By hi Attor cs. T. HART 2,619,661

CEMENT SOLE ATTACHING MACHINE USING HIGH-FREQUENCY 9 Sheets-Sheet 6 Filed Jan. 19, 1950 0 2 0 mHm e M ve 65 G Dec. 2, 1952 G. T. HART 2,619,661

CEMENT SOLE ATTACHING MACHINE USING HIGH-FREQUENCY Filed Jan. 19, 1950 9 Sheets-Sheet 7 Inventor Geofge THczr G. T. HART 2,619,661

CEMENT soLE ATTACHING mcmuz usmc; HIGH-FREQUENCY Dec. 2, 1952 9 Sheets-Sheet 8 Inventor George THarz, .53 hi Attorney .Filed Jan. 19, 1950 Dec. 2, 1952 G. 'r. HART 2,619,661

CEMENT sou: ATTACHING'MACHINE Ausmc HIGH-FREQUENCY Filed Jan. 19, 1950 9 Sheets-Sheet 9 Inve n for Gab/"5e T Ham Patented Dec. 2, 1952 CEIWENT SOLE ATTACHING MACHINE USING HIGH-FREQUENCY George T. Hart, Lynn, Mass, assignor to United Shoe Machinery Corporation, Flemington, N. J., a. corporation of New Jersey Application January 19, 1950, Serial No. 139,420

15 Claims. 1

This invention relates to high-frequency treating apparatus, and is herein illustrated as embodied in a dual machine for attaching soles to shoes by means of an adhesive or cement which may be activated by a high-frequency field. Usually, and as illustrated, one of the two stations will be arranged for left shoes and the other will be fitted for right shoes.

In attaching soles to shoes by means of adhesive, it is customary to apply an adhesive to both the bottom of the shoe and the attaching face of the sole, then to activate the adhesive upon at least one of these parts, to clamp the parts together under pressure and to hold them in clamped position for a period sufficient to allow the adhesive to set. Such machines are usually made with a plurality of stations for the reason that the interval of time required for the setting of the adhesive is sufiicient to permit an operator to prepare and clamp a number of shoes. Machines with eight and more stations are common.

One object of the invention is to provide an improved two-station apparatus, such as one for sole attaching, in which the activation of the adhesive is effected by means of a high-frequency electric field, and which will be safe to operate and convenient to use.

One important feature of such a machine relates to the use of movable shields, for covering the electrodes and the work at each station, which are interlocked so that only one station may be operated at any time, thus reducing the required size of the power supply and avoiding danger to the operator. In connection with this arrangement it is found desirable to employ one or more control switches, operated by the closing of the shield, and an electrically operated latch for holding the shield in closed position until the expiration of a predetermined interval when the latch is released and the power shut off, under the control of a timing apparatus.

Another feature of the invention especially applicable to the utilization of such a machine for attaching soles to shoes resides in a treadle-operated mechanism for clamping the work upon an inflatable pad and for dilating the pad only after sufficient pressure has been mechanically applied so that the pad will not be over expanded. Associated with this arrangement are safety devices preventing the release of the clamping device before the pad has been deflated. A hand lever for deflating the pad is rendered inoperative on the closing of the cover and a parallel linkage keeps 2 the lower surfaces of the work-contacting blocks parallel.

This is a continuation in part of my application Serial No. 85,618, filed April 5, 1949, now abancloned.

These are other features of the invention will best be understood from a consideration of the following specification taken in connection with the accompanying drawings in which Fig. l is a front elevation of a two-station machine embodying the present invention, with one shield closed;

Fig. 2 is a side elevation thereof;

Fig. 3 is a view in side elevation of the shoe clamping and supporting mechanism with the clamping pressure applied;

Fig. 4 is a section taken normal to the shoe support and with some parts shown in elevation;

Fig. 5 is an elevation of the parts of the clamping mechanism which lie beneath the top of the machine, viewed as if the top were horizontal;

Fig. 6 is a side elevation, on a smaller scale, of the two-part treadle lever;

Fig. 7 is a plan view of the electrode pad and its support;

Fig. 8 is a detail in vertical section showing a switch operated by the closing of the shield and connected between an oscillator and the electrodes at that station;

Fig. 9 is a detail in vertical section of a shieldlatchin mechanism;

Figs 10 and 11 are electrical diagrams showing the association of some of the electrical switches with the operating parts of the machine; and

Fig. 12 is an electrical diagram of a modification of the circuits illustrated in Figs. 10 and 11.

As may be seen from Fig. 1, the invention is embodied in a twin or two-station machine, having an angle-iron frame 8 (Fig. 2) which is covered by steel plates, the machine being provided with electrode pads l0 one of which is suitable for left shoes and the other for right shoes. Associated with each pad is a clamping mechanism, designed to be operated by a foot treadle I2, and a protecting cover-like electrical shield 16 hingedly mounted at l8 at the rear of the pads. Each of these shields is provided with an openin spring 20 and a buffer 22 to soften the action of the spring when the shield flies open. The shields are arranged to be closed by handles 24 and are held in closed position by latches, such as that shown at 26 in Fig. 9, which are urged by springs 21 to cooperate with notched pins 28 carried by the front of the shield.

To expedite the operation, the machine is ar- 3 ranged so that one sole is being attached while another shoe is being positioned and clamped at the other station. This enables the use of an oscillator only large enough for the treatment of one shoe at a time and to that end two protec tive devices are employed.

One of these comprises a resilient blade of a switch 33 (Fig. 8) supported beneath a cover plate 32 of the machine on an insulator 3d and adapted to be depressed into contact with a fixed plate 36 mounted on suitable supports including an insulator 38 and connected by a lead 3? to a tanl: coil (Fig. 11) in an oscillator 2%. This blade of the switch so is flexed down to close its circuit by means of a plunger is which is slidably mounted in a guide 42 and which has a head il above the top plate 32 in position to be engaged by a stud 55 carried by the side of the corresponding shield it. This switch is inserted between the high-frequency power supply and the electrode so that an electrode can only be energized when its shield is closed. Another protective device is mechanical and comprises a sort of whifiietree lever 5@ (Fig. 5) pivoted on a stud 52 beneath the top plate 32. This lever 58 has upstanding ends 5% and 5'5 vhich are alined with the side pieces of the respective shields (see also Fig. 1) so that when one shield is closed the other end of the lever projects above the top plate and prevents the closing of the other shield. The pivot stud 52 (Fig. 3) is threaded in one side :33 of a channel formed in inverted position in the under side of a casting, 6B which is attached to the under face of the top plate 32.

For the convenience of the operator the top plate 32 and the apparatus supported by it are inclined downwardly toward the operator. This top plate is carried by the frame 8 and at the front a shelf 62 (Fig. 2) is provided for temporarily supporting the work. A portion of this shelf lies in a recess fi l. Below the shelf is a front plate 66 (Fig. l) supporting an air pressure control handle (it and a toggle switch it) controlling the supply of power to the apparatus as a whole.

The activation of the cement used to attach the sole to the shoe may be efifected by means of any desired type of high-frequency electrode ll, one type illustrated in Fig. 7 being of the sort shown and described in Letters Patent of the United States No. 2,412,982, granted December 2%, 1946, upon my application. This electrode H comprises a series of loops l2 which are embedded in a rubber pad H- and are alternately connected to lead-in wires l6 and it, thus providing a series of stray fields extending above the pad which intersect a sole Stand the cement above it so that it may be attached to the shoe which in the illustrated form includes a platform sole E32 and an upper 84% mounted upon a last 8'5.

The electrode .pad rests upon a cushion 95 within a rigid frame 92 (Fig. 4) of dielectric material and the cushion is held in the frame by means of clamp plates t l and 95 (Fig. 7). The pad is held in position above it by U-shaped clamps 89 and overhanging clamps t3. Below the cushion 98 isa diaphragm Elli! (Fig. 4) which is clamped tightly by the frame G2 against a metal plate 5552 having a shallow central recess mil connected to a source of compressed air by means of a pipe we. The frame, diaphragm, and plate are clamped to the top plate 32 of the frame by means of screws such as those shown at (Fig. 7).

A mechanism for clamping the shoe firmly Al down upon its supporting pads is best shown in Figs. 3 and l and comprises a toe block I l0 resting on the toe and a heel block l 52 resting against the cone of the last, and also includes connecting parallel links for maintaining these members with their W0 .1 contacting surfaces always in planes substantially parallel to the surface of the pad. The parallel links comprise an H-shaped lower carrier arm M5 loosely pivoted upon a cross bar H6. The toe block and heel block are slidably mounted for adjustment in the under sides of holders 5 it and 52d having upstanding arms connected by a top link {122.

These holders are mounted on pivot rods E24 and H25 extending between the sides of the H- shaped member and their upper ends are joined by the upper link E22 which is fulcrumed by a pivot pin E28 on an upright arm [38 secured by means of a taper pin H322 to the rod H6. This rod passes through spacer sleeves I34 which, for convenience, are integral with the H-shaped link i it and its ends are positioned in slides 13%. One end of the rod H5 is fastened by a setscrew i238 so-that it may not rotate in the slides. These slides E35 are received in grooved ways in uprights ltd which are fastened to the top plate 32 by means of screws M2 (Fig. 3) long enough to extend through that plate and threaded into the casting 6% just beneath it which supports some of the apparatus positioned there.

The slides H36 are connected to ratchet blocks M 3 by means of rods M6 the ends of which are reversely threaded in the members which they connect. Springs M3 to lift the clamping apparatus are coiled upon the rods Hi5 and interposed between the bases of the uprights Hit and tension adjusting nuts M9 threaded on the rods. Associated with the ratchet blocks ltd are pawls I53, there being three at each side which are hung upon pivots I52 extending between one side 58 of the channel-like member underneath the top plate and the opposite side 59 thereof. The three pawls are of different lengths to secure different levels of engagement with the teeth of the ratchet so that the efiect is the same as if the ratchet teeth were much finer. These pawls are held against the ratchet blocks by leaf springs ifi i which are bent in a semicircle and then secured to 2. depending plate 55% fastened on the downwardly extending flanges H58 of the angle iron frame 8.

In order to pull down th clamps with substantial force the ratchet blocks its are connected to a foot treadle E2. This connection involves a cross rod it?! (Fig. 4) between the ratchet blocks and on this red there is mounted a sleeve I62 having a depending arm it'd. This arm is joined by a stud itt to one end of a lever iE-Z comprising the upper half of a two-part treadle lever see (Figs. 5 and 6). The other end ofthis upper half ted is fulcrumed upon a cross rod are carried by dep nding hangers Hi2 and il (Figs. 5 and 9) which are integral with the casting The hanger I72 is hook shaped, while the other hanger lid is more nearly straight. The near end of this lever 555 is shown in 5 and comprises a sleevelike portion around the rod 878. Between its ends, it has an outwardly xtending flange H8 (see also 8) with which there is associated a headed bolt itii passing through that flange and also through another flange 9S2 upon the lower half ii'iilof the treadle l ver ltd. This lower lever 55% is pivoted upon the other half of the rod I73 and is connected by a treadle rod We to the treadle l2. A rather heavy spring E33 surrounds the bolt I89 and is loaded to hold the flanges I18 and I32 normally in engagement.

When the treadle I2 is depressed the two parts I68 and 534 of the treadle lever I69 will be swung as a unit about the pivot rod I13 to pull downward the hollow square comprising the lower cross rod I68, the ratchet blocks led, the upright rods I45 and the slides I36 connected by the upper cross rod I I6, compressing the springs I48. This will bring the clamp blocks Ill] and H2 firmly against the shoe and its last and the clamp will be held against return motion by the pawls I52. When the resistance to downward movement exceeds the loading of the spring I88, the two parts of the lever will separate and in so doing will operate a switch Ill-3 (Figs. 3 and 6) which is attached to the lower part I84 of the treadle lever. The spring expelled button I92 in this switch, which is normally held down by engagement with a flange I94 secured to the upper half I58 of the treadle lever, will move upwardly and close the switch to permit operation of an air valve 290 as will later be explained. Beneath the foot treadle I2 is a stop as! (Fig. 2) and, if no shoe is in position on the pad, the movement of the treadle will not be great enough to bring the clamping blocks I I I1, I I2 against the pad and the switch I90 cannot be operated, thus protecting the pad.

This valve 206, mounted upon the frame 8 as shown in Fig. 2, is of a commercial construction and its exact structure is not shown but its mode of operation is indicated in the diagram of Fig. 10. From the diagram, the valve will be seen to comprise two valve members 202 and 294 the first of which is normally held closed by an associated spring and which controls the flow of compressed air from a sourc 2% to the pipe leading to the recess I8 5 beneath the diaphragm IEO. The other valve 284 which is closed when the first valve 202 is opened controls a passage leading to an exhaust 223 and the arrangement is such that this exhaust valve is closed when the inlet valve 202 is opened. The valve is arranged to be operated by a solenoid 2Iil connected between the opposite sides of power lines 2 I2. interposed in this connection is the normally open switch I90 and another switch 2 I4 which is normally closed.

After the shoe has been treated, the operator will release the air pressure by de-energizing the solenoid 2 Ill by opening the switch 2 I4 by means of a hand lever 220. This hand lever is mounted upon a rod 222 extending rearwardly of the machine in hangers 224 and 226 (Fig. 9) forming part of the casting 6 just under the top plate 32. On this rod between the hangers is an arm 228 having in it a screw stud adapted to wipe over a spring plate 236 which overlies the depressible switch button 2 I I. The latter is carried on a plate 232 which has two side members 234 and a hanger 236 which is fastened to an angle iron 238 forming part of the frame. Only a slight turning movement of the handle is required to operate this switch and upon a more extended movement th handle will be effective, as later described, to disengage the pawls I58 so as to allow upward movement of the shoe clamps. It is important however, that the pawls shall not be knocked off until the air has been mostly exhausted from the space beneath the diaphragm use.

Accordingly, a safety device is provided which is associated with the connections between the hand lever 22% and the pawl disengaging arrangement. The latter arrangement comprises swinging members 2:39 (Fig. 5) and 242 having knockoff pins 244 and 246 and the pins are arranged in recesses in the lower ends of the pawls I50, these recesses being larger than the pins to permit a slight movement of the handle 22!! sufficient to open the switch 2 I 4 which controls the air exhaust valve 294. The hangers which support the knockoff pins are connected by links 248 and 250 to the ends of an upright lever 252 which is secured by a setscrew to the far end of the shaft 222 on which the handle 22% is mounted.

In order to prevent the possibility of a movement of this hand lever 220 to release the clamp before the air has been exhausted from the pad, a detent 254 is provided which has a shoulder 25S adapted to cooperate with a roll 258 upon the link 248. After a slight movement of the handle 255 sufficient to open the air valve 2st by opening the switch 2I4, this roll comes against the shoulder 256 of the detent 254. The latter, pivotally supported at 2611 upon a hanger, has an upstanding arm 255 which is joined by a link 252 to the piston 264 of an air cylinder 266 connected by a pipe 275 to the space beneath the diaphragm I at. As long as there is air pressure in the cylinder, the detent 254 is held in the position shown in Fig. 5 but when the pressure has been relieved, as by the opening of the exhaust valve 284, then the detent is lowered by a spring 268 within the cylinder.

The operation of this air valve is eiiected by the solenoid 2I9 (Fig. 16) which, assuming that the switch 2M is closed, is energized whenever the switch let} on the two-part treadle lever I89 is permitted to close by the separation of these two parts because of pressure exerted on the treadle. At the same time a holding relay 214 is energized which supplies power to hold the air valve 262 open to inflate the pad even after the treadle has been released by the operator and until, at the completion of the operation, the hand lever 229 is moved slightly in a clockwise direction to open the switch 2H5. In order to make sure that the switch 2 I4 is normally closed at the beginning of a cycle a knob 2276 (Figs. 1 and 2) upon the front of the shield I6 is so positioned that it physically contacts the hand lever 220 and forces it to its left-hand position whenever the shield is closed, as shown at the right of Fig. 1.

As soon as a shoe has been clamped in position and the pad beneath it has been inflated to insure complete contact of the sole with all portions of the bottom of the shoe, which in this case would be the platform sole 82 just above the outsole 80, then the operator is ready to energize the electrodes so as to set up an electric field which will activate the cement and complete the attachment of the sole to the shoe. The operator, in starting to use the machine, will have closed the main switch Til and after a brief interval, a time delay relay 216 (Fig. 10) will have closed its contacts. This delay is intended to give the cathodes in the various tubes or" the power supply time enough to become heated before the power supply is required to furnish power to the electrodes.

Upon the closing of the main switch Ill, a yellow light Y will glow and then as soon as the time delay relay 216 has closed, turning on a green light G, a principal control relay 239 will be energized putting out the yellow light, the apparatus then being in a ready condition.

The operator will then close the shield to cover the work which has been adjusted and clamped on one of the electrode pads and in so doing the pin 28 upon the shield which is being closed will engage a lever 284 (Fig. 9) which will close a switch 286 (Figs. 9 and 10). This will close the circuit from the power mains 2I2 through the 7 upper contacts of 'the principal control relayZBil to energize axpower relay 288 which when lifted will connect the supply mains 2S2 to a power supply circuit 2'98 extending to one of the transi iormersiof a fullwave bridge-connected rectifier 292 (Fig 11) which is arranged to sup-ply direct current energy to an oscillator 29% having a tank coil-296. This tank coil will be connected by a lead 3? to an electrode associated with the shoe beneath the closed shield which latter will have closed one of the switches as shown in Fig. 8. Associated with'the plate circuit of the rectifier 2552 is a protective "plate "overload relay 2% while in the grid circuit of the oscillator there is a protective grid overload relay 3%. The contacts of these relays are in series with one another in a circuit 3% (Fig. 10) also containing the contacts of the time delay relay file and the contacts of a timer switch 384 adapted to be opened at the end of a predetermined interval by a timer 38% of any known construction, driven by power from the circuit 2%!) and automatically reset at the end of each cycle.

It will be noted that momentarily after the switch 285 has been closed by the closing of the shield there will be an energization of a solenoid 38:; arranged to release the latch 25. However, the circuit for this solenoid extends from the mains 2&2 through the lower contacts of the power relay 288, the plunger of which will be lifted almost immediately, thus allowing the shield to remain closed for the duration of the heating cycle and until the timer switch breaks the circuit to the green light G and to the principal control relay 28d and this turn de-energizcs'the power control relay 283 and the solenoids 3&8 will be energized to release the latch 26 and allow the shield to be opened. Opening of the shield opens the switch 28%; which when open prevents operation of the oscillator by preventing the'power relay 288 from being energized to supply high voltage power to the plate circuit of the oscillator. Th initial de-energiza tion of relay 283, by de-energizing switch 395 also returns the apparatus to the ready condition, but the cover i5 is unlatched to open before relay 288 is energized by the return of energizaticn to the relay 28! 'Should either of the grid or plate currents depart from-the predetermined range of magnitude in which the contacts of relays 298 and remain closed, for example, should themagnitude of the grid current increase sufficiently to open relay the interruption of the circuit 3532 causes a chain of events similar to that produced by opening of the timer switch, so that the cover is "opened and switch 28% prevents operation of the oscillator until the coveris again closed.

Assuming then that the switch it has been closed and that the yellow light Y is glowing, the operatorwill place a shoe on the pad at one station and clamp it by depressing the corresponding treadle. When suiii-cient pressure has thus been applied, the switch 196 on the treadle lever will be closed, energizing the air valve solenoid 2H) and inflating the pad. The holding relay 214 will keep solenoid 21E! energized even if the trea'd'le is released. Assuming that the other shield I6 is open and that the green light G is glowing, he then only needs to close the shield to cover the work thus closing the switches 30 and 286. This latter energizes the power relay 288 to supply power to the mains 29d and starts the timer 366. He then may leave this station and start to position a shoein the other station and to clamp it there while high-frequency powe is being applied to the first shoe to activate its cement. The completion of the interval required for this operation will be indicated automatically by the timer 3% which will then disconnect the power by opening the principal relay 280, thus de-energizing the power relay 288 and withdrawing the latch 25. He then may close the shield over the second shoe and proceed in the same manner. a

The modified circuit illustrated in Fig. 12 is adapted to provide additional protection against oscillator overload conditions, for example arcing between the electrodes, under which conditions the oscillator grid-current falls below normal. Accordingly, an undercurrent relay 3H) is shown in Fig. 12 connected into the grid circuit of the oscillatorin series with the relay'3ll0. The contacts of the undercurrent relay are in series with the connections between the upper contacts of the principal control relay 2% and the power relay 288. A normally open starting switch 3l2 is connected across the contacts of relay 3). With this arrangement, after the apparatus has warmed up and the green light G is glowing, the operator after placing a shoe under pressure may, as before, close the shield, covering the work and closing the switches 30 and'ZBB. However, the power relay 288 will not be energized, and hence the heating interval willnot start, until the starting switch 3l2 has been closed. Conveniently, this switchmay be arranged to be operated by a slight over-travel movement of the cover i8 beyond its normal closed position as the operator depresses the cover. However, the switch 312 maybe arranged to be actuated in any other convenient manner, for example, by one of the operators hands while the cover is held closed by his other hand. Closure of starting switch 312 now energizes the power relay 288 and supplies power to the mains 2% to energize the oscillator and to start the timer 305. The flow of the grid cur-rent in the oscillator will energize the relay 318 to close its contacts so that the starting switch 3l2 may be released without interrupting the operation of the apparatus and thereafter the apparatus will carry through the heating interval as described above. Should, however, a condition arise wherein the grid current falls below the pre-determined amount necessary to hold the contacts of relay 3 Ill closed, the power relay 288 will be de-energized, the oscillator shut oif and the cover unlatched by the ene-rgization of solenoid 308.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a high-frequencyelectric treating apparatus, a plurality of work-treating stations each comprising a work support, electrodes'positioned to create an electric field through a piece of work on said support, a movable electrical shield adapted, when in operative position, to cover the work and said electrodes, switchin means'controlling the connection of high-frequencyelectric energy from an energy supply means to said electrodes, and means connected to saidshield for actuating said switching means to supply power to the electrodes to treat the work only when said shield is moved into covering position, and means for limiting the numberof stations which may be operated at a given time, thereby to prevent overloading of said energy supply means.

2. In a high-frequency electric treating apparatus, a pad, means for pressin a piece of work against said pad, electrodes arranged to set up a field adjacent to the pad, a movable shield for covering the work and said electrodes, incomplete connections between an oscillator and the electrodes, electric contact means arranged to be closed by the closing of the shield, for completing said connections and for energizing a relay controlling said oscillator to supply power to said electrodes when the shield is closed, a solenoid released spring latch for said shield, and timing means associated with said relay for determining the heating interval following the closing of said shield, said relay being operative when dc-energized, to release the latch holding the shield closed.

3. In a high-frequency electric treating apparatus, an oscillator, a plurality of work heating stations individually comprising electrodes, means for positioning a piece of work within the field region of said electrodes, a movable shield for covering such a piece of work and its electrodes, and electric contact means controlled by said shield for connectin the electrodes to the oscillator only when the shield is moved to cover the work, and interlocks between said shields for determining the number of stations which may be operated at a given time.

4. In a high-frequency electric treating apparatus, a plurality of attaching stations individually comprising work supports and electrodes positioned in cooperative relation to said supports, a high-frequency oscillator, connections between said oscillator and the electrodes at the several stations, a switch at each of said stations in series with said connections, a switch at each of said stations closable for rendering the oscillator effective to supply power, means at each station for actuating both of said switches at that station, and means cooperating with the actuating means of all stations for pre venting simultaneous closure of the switches of more than one station.

5. In a high-frequency electric treating apparatus, multiple stations, electrodes at each station for producing a fleld in a piece of work, movable shields at adjacent stations adapted to be closed to cover said electrodes at the respective stations, interlocking means actuated by a shield as it is closed to prevent the closing or" another shield, and means actuated by the shield at each station, as it closes, for connecting a supply of high-frequency electric energy to the electrodes at said station.

6. In apparatus for cement sole attaching, a resilient inflatable work supporting pad, a cooperative clainping mechanism for applying initial pressure to a piece of work to clamp it against said pad, means for operating said clamping mechanism, spring means for determining the initial pressure of said clamping mechanism, a solenoid operated valve controlling the inflation and deflation of said pad, means for operating said valve to inflate said pad when said initial pressure exceeds a predetermined value, movable lever means to release the clamping mechanism, a switch for operating said valve to deflate said pad, said switch being actuated by the initial movement of said lever means, and means responsive to the fluid pressure in the pad for limiting further movement of said lever means until said working pressure has been reduced to a predetermined value, whereupon the move ment of the lever means may be continued to release the clamping mechanism.

7. Apparatus as in claim 6 in which said move- 10 ment-limiting means comprises a cylinder connected to said pad, a detent positioned for engagement with said lever means, a piston in the cylinder connected to said detent, and a spring for releasing said detent when the pressure in the cylinder is released.

8. In apparatus for cement sole attaching, an inflatable work supporting pad and a cooperative clamp for pressing a piece of work against said pad, a treadle for bringing said ciamp into pressure transmitting relation with the work against said pad, means operated by the movement of said treadle to inflate said pad, means to deflate said pad, and means operated by further movement of said deflating means for releasing said clamp, said latter two means being interconnected to prevent the clamp from being released before the pad is at least partly deflated.

9. In apparatus for cement sole attaching, an inflatable work supporting pad, a cooperative clamp for pressing a piece of work against said a treadle, a spring connected to said clamp to cause the clamps to draw the work against the pad, a valve to control inflation of the pad, means connected to said treadle to operate said valve when the tension in the spring exceeds a predetermined amount thereby to protect said pad against excessive expansion and to facilitate conforming it to the surface of the work, means for deflating said pad before said clamp is released, and means operated by said deflating means for releasing said clamp.

10. In apparatus for cement sole attaching, an inflatable work supporting pad, a cooperative clamp for pressing a piece of work against said pad, a treadle spring-connected to said clamp to draw the work against the pad, a valve to control inflation of the pad, means connected to said treadle to operate said valve when the tension in the spring exceeds a predetermined amount thereby to protect said pad against excessive expansion and to facilitate conforming it to the surface of the work, lever means for deflating said pad and then releasing said clamp, and pneumatically responsive means controlled by the pressure in the pad for limiting the movement of said lever to release said clamp until the pressure in the pad has been reduced to a predetermined value.

11. In apparatus for cement sole attaching, a work support, a cooperating clamp for pressing a piece of work against said support, pawls for retaining said clamp in work engaging position, a hand lever for releasing said pawls, a movable cover for the work, and means operated by the closing of the cover for resetting said hand lever to a position where it does not interfere with the effectiveness of said pawls.

12. In apparatus for cement sole attaching, an inflatable work supporting pad, means for inflating the pad, means including a hand lever for deflating the pad, a cover for the work movable into covering position, and means on the cover for rendering said hand lever inoperative when the cover is closed.

13. In apparatus for cement sole attaching, an inflatable work supporting pad, means for inflating said pad including a valve, a cover movable into position over the work and the pad, a hand lever controlling said valve to deflate the pad, and means on said cover for moving the hand lever to inoperative position as th cover is closed.

14. In a high-frequency electric treating apparatus, an inflatable, electrode-carrying pad, 2.

clamp for holding a piece of work against said pad, oscillator means for supplying high frequency' energy to the electrodes carried by said pad, means for moving said clamp to grip the work against said pad under an initial pressure, a switch actuated by said means upon the application of said initial pressure, pneumatic means controllable for inflating or deflating said pad and rendered efiective by the closing of said switch to inflate said pad and to press it against the work, a movable shield adapted to be positioned over the Work and said electrodes, a latch to hold said shield in effective position, a control switch actuated by the positioning of said shield, a power control relay operated by said switch to render said oscillator operative to treat the work, timing means for determining the treating interval, a timer relay, operated at the end of said interval, for disconnecting said power control relay and thereby releasing said latchin means, operator controlled means for controlling said pneumatic means for deflating said pad, and means for relieving the pressure of said clamp when the pressure in said pad has been reduced to a predetermined value.

15. In a high-frequency electric treating apparatus, a supporting frame and ofoperating stations carried thereby, each of said station's comprising an inflatable pad provided with electrodes, a clamp above said pad to grip a piece of work against said pad under pressure, a swinging shield carried at the top of said frame and adapted to be positioned over said'p'ad and the Work to prevent electrical radiation therefrom during operation; springmeans for holding said sh'ield normally open, means to operate said clamp to press the work against sa'idpad under an initial pressure, means for inflatingsaid pad when saidpr'essure has been attained, a highfrequency oscillator associated with. both stations to energize said electrodes atone station upon theflcl'osing of the shield at that station, interlocking'me'ans for preventing theclosing of both 'shields at thesame time, timing means for d'eter'miningthetreating interval at a station and for causing the release of said shield "when the work has beentreated, and means for successively deflating said pad and then releasing said clamp, 'to allow" the removal of the work from that station. GEORGE T. HART.

REFERENCES CITED The-following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,301,205 Finn Nov. 10, 1932 2,379,059 Ashley et a1 June26, 1945 2,401,277 St'ratton May 28, 1946 2,419,307 Zottu Apr. 22," 1947 2,442,451 Albin June 1, 1948 2,467,285 Young et al Apr. 12, 1949 2,473,188 Albin June'14, 1949 FOREIGN PATENTS Number Country Date 441,495 Great Britain Jan. 29, 1936 

